Vomiting, weight loss, diarrhoea and pain are common signs of intestinal disease in dogs and cats. There is plenty of area for things to go wrong, since an intestinal tract - if it were strung out end to end - is 8 to 10 times longer than its body! Diarrhoea can be acute (for 2–3 days) or chronic (for more than 3 weeks) and can also be a sign of other, extraintestinal systemic diseases. The most common cause of chronic diarrhoea in dogs, cats, and people is inflammatory bowel disease (IBD; Allenspach 2013; Simpson, Jergens 2011).

A good history is crucial in the evaluation of diarrhoea, and will usually determine whether the disease is acute or chronic, and whether involving the small or large intestine (Table 1).

Table 1. Clinical signs of small and large bowel diarrhoea

Table 2. Likelihood of common differential diagnoses in acute and chronic diarrhoea, according to history. IBD: inflammatory bowel disease, SIBO small intestinal bacterial overgrowth, EPI exocrine pancreatic insufficiency, ARD antibiotic responsive diarrhoea, PLE protein losing enteropathy, AFR adverse food reaction

There are many differential diagnoses for diarrhoea in dogs and cats (Table 2). Animals with acute or chronic diarrhoea that are bright and happy, with no intestinal bleeding, are most likely to have an adverse food reaction (AFR), a parasite (e.g., T. foetus, Giardia, Ancylostoma), small intestinal bacterial overgrowth (SIBO), exocrine pancreatic insufficiency (EPI), lymphangiectasia or mild IBD. Addison's and lymphoma can catch you out here, but other parameters, such as age and breed will help - older animals are more likely to have lymphoma, and susceptible breeds to Addison's disease include the Rottweiler, Poodle, Leonberger, and German short haired pointer. Chronic intestinal haemorrhage is caused by severe pathology and an ulcerated mucosa, likely severe IBD or a tumour. In Boxer dogs and French bulldogs, this is probably Granulomatous colitis. (Craven et al. 2010; Craven, Mansfield, Simpson 2011; Simpson et al. 2006). Table 3 describes the tests most utilized for diagnosis of diarrhoea. (Allenspach 2013; Jergens 1999; Simpson, Jergens 2011; Jergens, Simpson 2012).

Treatment Tips

1. Diet

In recent years, the importance of diet in the management of dogs and cats with chronic intestinal disorders such as IBD has received much attention. (Jergens 1999; Simpson, Jergens 2011). Pets are often fed the same food brand for many years without variation. This completely unnatural existence could potentially cause development of intolerance to many types of food antigens and prime the mucosal immune system for an inflammatory state and bacterial dysbiosis. This could predispose to adverse food reactions (AFR), IBD, small intestinal bacterial overgrowth (SIBO), antibiotic responsive diarrhoea (ARD), and protein-losing enteropathy (PLE). Dietary change is, in the author's opinion, an integral and very overlooked aspect to management of all chronic GI diseases. Feeding a more varied diet can help to reestablish antigenic tolerance, but clinical signs can sometimes worsen before improving. A home-cooked diet in all cases, for 7–10 days, whether clinical signs are acute or chronic, is suggested, and achieves very good results in the author's experience. Withholding food is not helpful unless there is intractable vomiting.

 Day 1: 3 meals of boiled white rice, spinach, white fish, pinch salt, butter

 Day 2: 3 meals of boiled potatoes, broccoli, tofu, olive oil

 Day 3: 3 meals of pasta, green peas, ham, pinch salt, butter

When clinical signs have resolved, which can take as little as 2–3 days, reintroducing a dog kibble alongside some long-term variation of the above is suggested. If the animal remains systemically well, but clinical signs do not resolve within 7 days, it is unlikely to respond to diet change alone, and further diagnostics and targeted treatment are needed. The author invariably approaches treatment of IBD, PLE, ARD, SIBO, and "IBS" in this way with excellent results.

2. Interventional Feeding

In protein-losing enteropathy (PLE), an abnormal loss of albumin occurs through the gastrointestinal (GI) mucosa, above the rate of compensation by liver synthesis. Differentials include inflammatory bowel disease (IBD), intestinal lymphoma, and lymphangiectasia. The Yorkshire terrier, Soft-coated Wheaten terrier and Rottweiler are predisposed (Dossin, Lavoué 2011; Simmerson et al. n.d.).

We have little understanding of PLE, and treatment is best guess with steroids, cyclosporine and antibiotics, (author estimates 50% response rate). Pleural and peritoneal effusions are common, and clotting problems can resulting in sudden death due to thromboembolic disease, likely to be caused by poor vascular repair and inability of the liver to produce/retain anticoagulatory proteins. It is vital, therefore, that these animals are fed a high-protein diet. For the best chance of response, the author prefers to place a feeding tube very quickly, preferably an esophagostomy tube. Appetite in PLE cases is usually very unreliable, and vomiting can usually be controlled using antiemetics, e.g., ondansetron and/or maropitant. Surgical placement of a well-secured esophagostomy tube is easily achieved at the time of anaesthesia for endoscopic biopsy. A surgically placed gastrostomy tube is an alternative, though with greater risk of peritonitis due to poor wound healing. Administering 5–10 g per kg bodyweight of protein, e.g., casein, whey, or pea protein powder, can achieve significant improvement alone in the author's experience, without the addition of drug therapy. PLE is a very difficult condition to treat, with much time and energy and tremendous anxiety generated in simply trying to get these animals to eat. The sooner that nutrition can be administered in a controlled manner, the better the chances of survival. Greatest success in the author's experience has been achieved in this way, alongside the use of cyclosporine (5 mg/kg every 12 hours) and ultralow-dose aspirin (0.5 mg/kg every 12–24 hours).

3. Therapeutics

Medical therapies often used to treat acute and chronic diarrhoea include prednisolone; budesonide (IBD, lymphoma, PLE); cyclosporine; and the antibiotics metronidazole, tylosin, and enrofloxacin (ARD, SIBO, EPI) with varying success. In the author's experience, acute diarrhoea can be treated without drug therapy unless there is GI haemorrhage. In this case, protection of the mucosal barrier is indicated with sucralfate, omeprazole and 3–5 days of an antimicrobial such as a tetracycline or a fluoroquinolone, to reduce opportunist pathogens which are most likely to translocate). Most cases of chronic diarrhoea can be addressed with dietary change, when there is no indication for targeted treatment (pancreatic enzymes, chemotherapy). A recent study also showed that probiotics (VSL3) had a significant protective effect in 20 dogs with IBD (Rossi et al. 2014).

Table 3: Tests commonly used in diagnosis of acute and chronic diarrhoeas in dogs and cats

References

1.  Allenspach K. Diagnosis of small intestinal disorders in dogs and cats. Vet Clin North Am Small Anim Pract. 2013;43(6):1227–1240, v. doi:10.1016/j.cvsm.2013.07.001.

2.  Craven M, Dogan B, Schukken A, Volkman M, Chandle A, Mcdonough PL, Simpson KW. Antimicrobial resistance impacts outcome in granulomatous colitis of boxer dogs. J Vet Int Med. 2010;819–824.

3.  Craven M, Mansfield CS, Simpson KW. Granulomatous colitis of boxer dogs. Vet Clin North Am Small Anim Pract. 2011;41(2):433–445. Retrieved from www.ncbi.nlm.nih.gov/pubmed/21486645.

4.  Dossin O, Lavoué R. Protein-losing enteropathies in dogs. Vet Clin North Am Small Anim Pract. 2011;41(2):399–418. doi:10.1016/j.cvsm.2011.02.002.048.

5.  Jergens AE. Inflammatory bowel disease. Current perspectives. Vet Clin North Am Small Anim Pract. 1999;29(2):501–521, vii. Retrieved from www.ncbi.nlm.nih.gov/pubmed/10202800.

6.  Jergens AE, Simpson KW. Inflammatory bowel disease in veterinary medicine. Front Biosci (Elite Ed). 2012;4:1404–1419. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/22201965.

7.  Ross G, Pengo G, Caldin M, et al. Comparison of microbiological, histological, and immunomodulatory parameters in response to treatment with either combination therapy with prednisone and metronidazole or probiotic VSL#3 strains in dogs with idiopathic inflammatory bowel disease. PLoS One. 2014;9(4):e94699. doi:10.1371/journal.pone.0094699.

8.  Simmerson SM, Armstrong PJ, Wünschmann A, Jessen CR, Crews LJ, Washabau RJ. Clinical features, intestinal histopathology, and outcome in protein-losing enteropathy in Yorkshire Terrier dogs. J Vet Intern Med. 2014;28(2):331–337. doi:10.1111/jvim.12291.

9.  Simpson KW, Dogan B, Rishniw M,  et al. Adherent and invasive Escherichia coli is associated with granulomatous colitis in boxer dogs. Infection and Immunity. 2006;74(8):4778–4792. Retrieved from http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1539603&tool=pmcentrez&rendertype=abstract.

10. Simpson KW, Jergens AE. Pitfalls and progress in the diagnosis and management of canine inflammatory bowel disease. Vet Clin North Am Small Anim Pract. 2011;41(2):381–398. doi:10.1016/j.cvsm.2011.02.003.